Hand-operated,belt-type sanding device for woodworking



HAND-OPERATED, BELT-TYPE SANDING DEVICE FOR WOODWORKING Filed April 25, 1966 O. BERGLER March 11, 1969 Sheet RE w a P r m r r 0 w 4 March 1969 o. BERGLER 3,431,686

HAND-OPERATED, BELT-TYPE SANDING DEVlCE FOR WOODWORKIRQU' Filed April 25, 1966 Sheet 2 of 4 March 11, 1969 o. BERGLER 3,431,686

HAND-OPERATED, BELT-TYPE SANDING DEVICE FOR WOODWORKING Filed April 25, 1966 Sheet 3 of 4 IN VEN TOR. 0770 559645? 0. BERGLER March 11, 1969 HAND-OPERATED, BELT-TYPE SANDING DEVICE FOR WOODWORKING Filed April 25, 1966 Sheet 4 of INVENTOR. 077'0 BZPGZZZ United States Patent 3,431,686 HAND-OPERATED, BELT-TYPE SANDING DEVICE FOR WOODWORKING Otto Bergler, Lomersheim, near Muhlacker, Germany, assignor to Eugen Lutz KG., Maschinenfabrik, Muhlacker-Lomersheim, a corporation of Germany Filed Apr. 25, 1966, Ser. No. 545,060 Claims priority, application Germany, Apr. 24, 1965, L 50,559 U.S. Cl. 51170 18 Claims Int. Cl. B24b 23/00 ABSTRACT OF THE DISCLOSURE A hand-operated belt sanding machine comprising a housing having a driving motor and a pair of sanding belt rollers rotatably supported thereon with at least one of the rollers being drivingly connected to the motor. A sanding belt is supported on and extends between the belt rollers. A sanding belt pressure plate is mounted on the housing in a fixed position relative to the belt rollers. A guide frame surrounds the active portion of the sanding belt and is connected to the housing by a parallelogram linkage for permitting relative movement between the guide frame and the pressure plat while maintaining the guide frame substantially parallel to the pressure plate. Adjustment means coact between the housing and the guide frame for adjusting the height of the pressure plate relative to the guide frame.

The invention relates to a hand-operated belt sanding machine for wood-working purposes, the essential components of which are a housing, in which are accommodated the driving motor, the two sanding belt rollers and the sanding belt pressure plate, and attached to the same, a guide frame which can be placed on the work piece, and encloses the belt rollers and the pressure plate.

In the sanding belt machines of this known design, the sanding belt pressure plate is arranged within the housing in a manner such as to be adjustable as to its height in relation to the sanding belt rollers. With this arrangement, the control of the sanding belt is difficult, since the sanding belt slides laterally off the rollers, even with only a slight diagonal misalignment of the pressure plate, which is caused by the inevitable play of the bearings and wear. Moreover, the proper parallel alignment of this pressure plate in relation to the quide frame and the accurate parallel adjustment to this frame, are complicated mathe sanding pressure and cutting depth are often uneven.

To obviate the aforementioned disadvantages, the invention is based on the idea of employing a basically known sanding device, in which the sanding belt pressure plate is arranged in the housing, stationary in relation to the rollers, and connecting this sanding device and housing to the guide frame in a manner such as to provide the facility of a parallel vertical adjustment in height between the housing and the guide frame and, in this way, a variation in sanding pressure or cutting depth, respectively. Accordingly, the sanding belt pressure plate, in the case of the belt sanding machine following the invention, is arranged, in a basically known manner, stationary within the housing and in relation to the rollers, and the guide frame is attached to the housing in a manner such as to be adjustable while remaining parallel to the pressure plate, and a control mechanism is arranged between the housing and the frame, which enables the housing and, thus, the pressure plate to be adjusted in their height in relation to the frame. This novel design and arrangement ensure a proper parallel alignment of the pressure plate to the guide frame, whenever the height may be varied,

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nipulations in the case of this design, as a result of which and the result is a constant sanding pressure or a constant cutting depth as well as a proper operation of the belt. To provide a small and handy belt sanding machine which gives high sanding performance with a relatively low weight, this belt sanding machine is of such a design that a roller is driven by a horizontal-type small and high-speed motor, via a transmission gear. Since this transmission gear projects beyond the side of the machine housing, the guide frame of such a belt sanding machine would have to bulge at one side around this laterally projecting gear case. To obviate this and to enable a guide frame to be designed in a rectangular cross section, which tightly encloses the rollers and the sanding belt, a longitudinal groove is arranged, according to the invention, in the lower part of the housing between one of the rollers and the gear wheel driving the same, and fitting into this groove is the one side of the rectangular frame.

Further details of the invention and its advantages are described below with reference to various practical examples shown in the drawings:

FIG. 1 gives a side view of a belt sanding machine with guide frame, partially in a section following the line I-I of FIG. 3,

FIG. 2 gives a cross section following the line IIII of FIG. 1,

FIG. 3 shows the guide frame of FIG. 1 in a top view,

FIG. 4 gives a partial view in direction of arrow IV in FIG. 1, on an enlarged scale,

FIG. 5 shows a broken, partial cross section following the line VV of FIG. 4,

FIG. 6 is a section following the line VIVI of FIG. 5,

FIG. 7 shows components of FIG. 4, in a different position,

FIG. 8 shows an alternative of the guide frame, viewed in a section according to FIG. 2,

FIG. 9 gives a view in direction of arrow D( in FIG. 8, and

FIG. 10 shows in a diagrammatic view a modified hearing of the housing on the guide frame.

In the drawing, 1 denotes a housing fitted with a handle 2 and a knob 3, in which are accommodated the driving motor 4, the two rollers 6 and 7, surrounded by the sanding belt 5, and the sanding belt pressure plate 8. The latter is secured to the housing in a rigid arrangement, i.e. stationary in relation to the rollers 6 and 7. Furthermore included is a guide frame '9 which can be placed on the work piece, and encloses the rollers 6, 7 and the pressure plate 8. The housing 1 is assembled to this guide frame by means of parallel rods 10 and 11 which, together with the housing and the guide frame, form a parallelogram linkage system. A control mechanism 1'2 is arranged between the housing and the frame, which permits the variation of the angular position of the parallel rods, as indicated by the angle at, and thus the adjustment of the height of the pressure plate 8 as related to the frame 9.

In the preferred embodiment shown, the rods 10 and 11 are in the form of parallel cranks, arranged at both ends of transverse shafts 13, 14. These two transverse shafts 13 and 14 are pivoted in the housing 1, and the cranks 10, 11 are fitted with crank pins 15, 16 which, in turn, are pivoted in the frame 9. The transverse shafts 13, 14 and the crank pins 15, 16 are supported in open bearings 17 and 18 of substantially semi-cylindrical shape, which are arranged at the housing 1 and the frame in a manner such that the housing 1 can be lifted off and removed from the frame 9. Clamping springs 19 at the frame and a clamping spring 20 at the housing secure the crank pins 16 and the transverse shaft 14 so as to prevent the frame from being detached from the housing under its own weight.

As can be seen from the drawing, the transverse shaft 14 is in a rigid mount in the housing v1 between the pressure plate 8 and the roller 7, and its crank pins 16 brace against the semi-cylindrical bearings 18 of the frame and can be released, whilst the crank pins 15 of the other transverse shaft 13 are in a rigid mount at the frame 9 (cf. FIG. 3), and the housing 1 is supported on this transverse shaft 13 by the semi-cylindrical bearings 17 in a detachable assembly. The housing is fitted with clamping springs, not shown in the drawing, which, similar to the clamping spring 19, secure the transverse shaft 13 and prevent an accidental detaching of the frame from the housing. This means that, if the frame 9 is to be removed from the housing 1, the frame 9 is held fast by hand and the housing is lifted off, with the transverse shaft 13 remaining in the frame, whilst the crank pins 16 of the transverse shaft 14 of the housing are withdrawn from the clamping springs 19. The above mentioned control mechanism includes a spring which normally locks the housing -1 in its adjusted height in relation to the frame 9; the tension of this spring is, however, overcome when an increased pressure by hand is applied on the handle 2 and the knob 3 in direction V, so that the distance in height between the housing 1 and the frame 9 is reduced and, consequently, the sanding pressure is increased.

As can be seen from FIGS. 1 and 3, the control mechanism 12 is preferably supported by the frame, and its setting member 21 acts on the transverse shaft 13. This setting member comprises a threaded spindle fitted with a boss-type head 22 which is split at a slot 23 so that it can be pushed on the shaft 13, and as can be seen from FIG. 1, encloses the transverse shaft 13. Furthermore, a threaded sleeve 24 is screwed on this spindle 21 and pivoted in a cross piece 25, but secured against axial displacement. This cross piece 25 is supported in two cars 26 of the frame 9 and can be turned around the horizontal axis a, which is in parallel to the transverse shaft 13. This threaded sleeve 24 is surrounded by a helical compression spring 27 which braces, at the one end, against the sleeve head 28 and, at the other end, against the cross piece '25, at 29. The grooved cap knob 32 which encloses and covers the helical spring 27 is tightly secured to the outer end of the sleeve 28 by means of a pin 31 or the like. By turning this grooved cap knob in either direction, one can move the setting member 21 in direction B or C so as to vary the angular position a. of the rods 10, 11 and with this the height of the pressure plate 8. When applying an additional pressure by hand, on the housing in direction V, one overcomes the pressure of the spring 27 and shifts the threaded sleeve 24 together with the setting member 21 in the direction B, which means a reduction of the angle on and consequently, an increase in sanding pressure.

The transverse shaft 14, arranged between the pressure plate 8 and the roller 7, can be shifted within the housing in an axial direction, as can be seen from FIGS. 4-7, i.e., it can be shifted from the normal position shown in FIGS. 4 and 5, in direction D (FIG. 7), after removal of the frame 9, so that its crank 16, which extends beyond the edge 33 of the belt can be returned so as to be positioned behind this edge, as shown in FIG. 7. The transverse shaft 14 and the aforementioned crank 16 do not cause therefore any obstruction to the belt sanding operation when the sanding machine is used without the frame 9.

As demonstrated in FIGS. and 6, the transverse shaft 14, which can be shifted in the axial direction, is tightly held in place in the semi-cylindrical bearings 17 by the above mentioned clamping spring 20 so as to be secured in both its axial and rotary position. This transverse shaft 14 is furthermore fitted with a tangential keyway 34, and the housing is provided with a cam 35 which fits into this keyway, and is arranged in such a manner as to secure the shaft to the bearings 17 in the operative position, as can be seen from FIGS. 4-6; when the shaft is, however, shifted in the axial direction E, the keyway 34 and the cam 35 will coincide, which allows the shaft 14 to be removed from the bearings 17 in direction V. In the case of the illustrated preferred embodiment, the projecting cam 35 is the head of a screw 36 which serves for tightening the clamping spring 20.

The arrangement and the design of the transverse shaft 14 in the housing as described above, thus provide the alternative of either supplying and using the belt sanding machine in the assembly of the components 1 to 8 as a self-contained unit, or operating this belt sanding machine in conjunction with the guide frame 9, by simply attaching the transverse shaft 14.

In the particularly preferred example shown, the belt sanding machine is equipped with a motor 4, which drives the roller 6 via a reduction gear, arranged in the part 1a of the housing; this transmission takes place via a gear wheel 37 arranged on the shaft 38 of the roller 6. In this Way, one can use a rather small high-speed motor 4 so as to arrive at a relatively small and handy belt sanding machine. In this case, the housing In of the reduction gear is extended, however, to a very low-extending bottom part 1b which encloses the gear wheel 37. According to the invention, a longitudinal groove 39 is arranged in the bottom of the housing 1, between the roller 6 and the gear wheel 37 driving this roller, and a longitudinal flange 40 of the frame fits into this groove, so that also in the case of such a belt sanding machine equipped with a reduction gear, a rectangular frame 9 which tightly en closes the rollers 6 and 7, can be provided for. As can be seen from the drawing, this frame is of an L-profile of the width b on one side, whilst the other side 40 of the frame, which fits into the groove 39, is of a rather narrow square section of the width 0 which allows this longitudinal groove to be kept to a relatively small width.

To adapt the belt sanding machine together with the guide frame 9, as described above, so that it can be used as well for grinding rebates or floor corners and the like, a special design is shown in FIGS. 8 and 9, in which the guide frame 9a, at the side of the belt edge 33, is bent twice at right angles, once in a vertical and once in a horizontal outward direction, such that the upright frame legs 42 are flush with the belt edge, indicated at 43, and the side rails 45 of the frame, which is held by the horizontally bent leg 44, is arranged at a larger distance it from the frame base.

As for the example shown in FIG. 10, those components of the machine which are in conformity with the above mentioned components, are denoted by the same symbols, but with an afiix 0.

Instead of supporting the housing on the guide frame by means of parallel rods 10, 11, as described above (cf. FIG. 1), one can also utilize eccentric discs 10c, 110, which are at some distance from each other and pivoted on the guide frame at 15c, 160, as shown in the diagrammatic view of FIG. 10. The housing 10 rests on these eccentric discs. One of these eccentric discs is actuated by the aforementioned control mechanism, which is attached to the frame and represented in a diagrammatic way in FIG. 10 by the push rod 210 which is hinged to the eccentric disc 10c at 58.

What is claimed is:

1. A hand-operated belt sanding machine, comprising a housing, a driving motor in said housing, two sanding belt rollers rotatably mounted on said housing and adapted to support a sanding belt thereon with said sanding belt having an active portion extending between said sanding belt rollers, means driveably connecting at least one of said rollers to said motor, a sanding belt pressure plate mounted on said housing in a fixed position relative to said belt rollers, a guide frame surroundnig the active portion of said sanding belt, mounting means including parallelogram linkage means for connecting said guide frame to said 'housing for permitting relative movement between said guide frame and said pressure plate while maintaining said guide frame substantially parallel to said pressure plate, and adjusting means coacting between the housing and the guide frame for enabling the housing and the pressure plate to be adjusted in height relative to the said guide frame.

2. A belt sanding machine according to claim 1, further including a speed reduction gear unit between said motor and said one belt roller, and wherein a longitudinal groove is arranged in the housing between said one belt rollers and a gear wheel driving same, and a longitudinal part of said frame fits into said groove.

3. A belt sanding machine according to claim 1, Wherein said mounting means includes at least two parallel members pivotally coacting between said frame and said housing and defining said parallelogram linkage means.

4. A belt sanding machine according to claim 3, wherein each of the parallel members comprises a transverse shaft mounted in the housing and having parallel cranks at opposite ends thereof, and further including crank pins pivotally connecting each of the cranks to the frame.

5. A belt sanding machine according to claim 4, wherein one of said housing and said frame is fitted With open bearings to pivotally support the transverse shafts and the crank pins in a manner such as to allow the housing to be detached from the frame by being lifted off.

6. A belt sanding machine according to claim 5, said mounting means including clamping springs acting on the transverse shafts and the crank pins to prevent the frame from being detached from the housing by its own weight.

7. A belt sanding machine according to claim 5, wherein one of said transverse shafts is in a fixed mount in the housing between the pressure plate and a belt roller and its crank pins bear against semi-cylindrical bearings formed on the frame, from which position they can be released, while the crank pins of the other transverse shaft are fixedly secured to the frame, and the housing has semi-cylindrical bearings which rest in a detachable manner on said other transverse shaft.

8. A belt sanding machine according to claim 1, wherein the adjustment means includes a spring which normally locks the housing in its adjusted height in relation to the frame but yields under increased pressure ap plied on the housing by hand so that the height is reduced and therewith the sanding pressure is increased.

9. A belt sanding machine according to claim 4, wherein the adjustment means is supported by the frame and includes a setting member which acts on one of the transverse shafts.

10. A belt sanding machine according to claim 9, wherein the setting member comprises a threaded spindle with a boss-type head which partially surrounds said one transverse shaft, and a threaded sleeve which is pivoted in a cross piece in the frame but locked against axial displacement, said threaded spindle being engaged in said sleeve.

11. A belt sanding machine according to claim 10, wherein a helical compression spring surrounds the threaded sleeve and bears at one end against the outer end face of the sleeve and at its other end against the cross-piece, and the inward end of the sleeve bears against the cross-piece through a spacer.

12. A belt sanding machine according to claim 11, wherein the outward end of the sleeve is secured to a grooved cap knob which encloses the helical spring.

13. A belt sanding machine according to claim 7, wherein one of said transverse shafts is axially adjustable in the housing such that its crank, which projects beyond a front edge of the belt, can be pushed backward so as to be positioned behind this edge.

14. A belt sanding machine according to claim 13, wherein the axially adjustable transverse shaft is tightly held in the semi-cylindrical bearings by a clamping spring, both as to its axial and its rotational position.

15. A belt sanding machine according to claim 14, wherein the one transverse shaft is provided with a tangential keyway and a cam fitting into same and arranged at the housing in such a manner that the transverse shaft is secured in the bearings when in an operative position, but when shifting the transverse shaft in axial direction, the keyway and the cam will coincide, so that this shaft can be withdrawn from the bearings.

16. A belt sanding machine according to claim 15, wherein the cam is the projecting head of a screw which secures the clamping spring to the housing.

17. A belt sanding machine according to claim 2, wherein the guide frame at one side of the housing adjacent the belt edge is bent twice at right angles, once in a vertical and once in a horizontal outward direction .such that the vertically bent frame portion lies flush with the front edge of the belt, and a side rail of the frame is held by the horizontally bent frame portion at a larger distance from the frame base.

18. A belt sanding machine according to claim 1, wherein the parallelogram linkage means includes laterally spaced eccentric discs pivotally mounted on the guide frame.

References Cited UNITED STATES PATENTS 1,172,828 2/1916 Osgood 4 1,370,441 3/1921 Henderson 51-170 1,410,554 3/1922 Dernbach 145-4 1,418,328 6/1922 Power 14-54 1,707,584 4/ 1929 Swan 51-17O 2,289,481 7/ 1942 Burleigh 51-170 2,894,549 7/1959 Garland 145-4 3,176,436 4/1965 Anton 51--170 LESTER M. SWINGLE, Primary Examiner.

D. G. KELLY, Assistant Examiner. 

